Ultrasonographic process

Abstract

 The invention concerns an ultrasonographic process wherein a visible image corresponding to a pattern of ultrasonic exposure is formed in a silver halide element.
According to this process, an element comprising internally fogged silver halide grains is contacted with a transport liquid in the presence of a solute (for example, a silver halide solvent or iodide ions) capable of rendering the internally fogged silver halide grains developable in a silver halide developer. The element is then imagewise ultrasonically exposed and developed in a surface developer to produce a visible image defined by the pattern of ultrasonic exposure. The sensitometric curves show that the higher the solute concentration, the better the sensitivity of the element.

Description

[0001] This invention relates to an ultrasonographic process. More specifically, this invention is directed to a process of forming a visible image in a silver halide element through the use of imagewise ultrasonic alteration of a silver halide emulsion layer and conversion of such ultrasonically induced alteration of the emulsion layer to a viewable image.

[0002] The term "ultrasonic radiation" is employed herein to designate pressure-rarefaction waves differing from sound waves in exhibiting higher frequencies and shorter wavelengths. Other grammatical variations of the nomenclature concerning ultrasonics that are used herein are consistent with those used in the art. Specifically, these terms are suggested by P. J. Ernst in the Journal of the Accoustical Society of America, Vol. 22, No. 1, in an article entitled "Ultrasonography", pp. 80-83, January 1951.

[0003] The prior state of the art with respect to the action of ultrasound on silver halide photographic elements is reviewed by M. E. Arkhangel'skii, Soviet Physics-Acoustics, Vol. 12, No. 3, "Action of Ultra- sound on the Process of Photographic Development and Fixing", pp. 241-248, January-March 1967. The ability of ultrasound exposure to produce a latent image in silver halide emulsions has been previously recognized as reported by Arkhangel'skii. However, power level requirements to achieve ultrasonic imaging have been quite high, it is uncertain as to whether the ultra- sound directly produces the latent image or stimulates other effects, such as cavitation-stimulated lumine- sence, which produce the latent image. It has been recognized that higher maximum densities are attainable for a given power level of ultrasonic exposure when the photographic element is in contact with a photographic developer. Arkhangel'skii observed that if the photographic element is first light exposed and then ultrasonically exposed in a developer, the ultrasonic time and intensity to produce a density obtainable in the absence of light exposure decrease to a few minutes and a few watts per square centimeter, respectively.

[0004] It has been a problem in the art that ultrasonic exposure requirements of silver halide photographic elements, even with the most responsive techniques known, have remained unattractively high. For example, such techniques have required intensity and time levels of ultrasonic exposure which are objectionable to many non-destructive testing applications, such as mammographic examination with ultrasound as described in U.S. Patent 3,765,403.

[0005] The present invention relates to an ultrasonographic process for preparing visible images that can be carried out with low levels of ultrasonic exposure. The process uses an element comprised of a support having a silver halide emulsion layer, and which process comprises exposing the element to ultrasound in an image pattern while the element is in contact with a liquid, and developing the element with a silver halide developer to produce a^lvisible image defined by the ultrasonic exposure, characterized in that the silver halide emulsion contains internally fogged silver halide grains, the liquid is a transport liquid for a diffusible solute capable of rendering the internally fogged silver halide grains developable in a surface developer. The exposure to ultrasound accelerates imagewise diffusion of the solute into contact with the internally fogged silver halide grains.

[0006] The invention can be further explained by reference to the following detailed description considered in conjunction with the drawings, in which

Figures 1 and 3 through 6 are plots of density versus ultrasonic exposure and

Figure 2 is a plot of density versus immersion time.

[0007] To form an ultrasonograph according to this process any ₃ilver halide element can be employed comprised of a support and, coated thereon, at least one silver halide emulsion layer which contains internally fogged silver halide grains. Such elements are hereinafter designated internally fogged silver halide elements.

[0008] The internally fogged silver halide elements are capable of producing a visible density when developed in an internal developer and are sufficiently free of surface fog that they produce a readily visually discernable lower density when developed in a surface developer as compared with an internal developer. For instance, the internally fogged silver halide elements are preferably capable of producing a density of at least 0.5, most preferably at least 1.0, when processed for 5 minutes in Reference Internal Developer A at 25°C. When processed for 5 minutes in Reference Surface Developer B at 25°C such elements are preferably capable of producing a density of at least 0.2, most preferably at least 0.8, less than when comparably processed with Reference Internal Developer A.

[0009] In a specifically preferred form,the internally fogged elements are sufficiently free of surface fog that they produce a density of less than 0.1 when processed for 5 minutes in reference Surface Developer B at 25°C.

Reference Internal Developer A

[0010] 

Reference Surface Developer B

[0011] 

[0012] Internally fogged silver halide elements suitable for use in this process can be provided by the selection or modification of known silver halide photographic elements. For example, photographic elements which contain both surface-sensitive emulsions and internally fogged, internal latent image-forming emulsions are disclosed by U.S. Patents 2,996,382, 3,178,282, 3,397,987; 3,705,858; 3,695,881; Research Disclosure, Vol., 134, June 1975, Item 13452; Millikan et al U.S. Patent Office Defensive Publication T-0904017, April 21, 1972 and Research Disclosure, Vol. 122, June 1974, Item 12233. The surface-sensitive and internally fogged emulsions are blended or coated in separate layers. Where the coating coverage of the internally fogged emulsions is sufficient to provide a density of at least about 0.5 in Reference Internal Developer A, as described above, these photographic elements can be employed without further modification . in this process. In a preferred form these photographic elements are modified to omit the surface-sensitive emulsions, since they do not contribute to imaging in the present process and offer the disadvantage of rendering the elements light-sensitive. It is preferred to increase the coating coverages of the internally fogged emulsions in these elements, since these emulsions are alone being relied upon to produce a visible image, rather than working in combination with the surface-sensitive emulsions as these elements are conventionally employed.

[0013] The internally fogged silver halide elements employed in this process can also be prepared merely by exposing conventional photographic elements of the type which form internal latent images. By uniform light exposure, for example, such conventional internal latent image-forming elements are converted to internally fogged silver halide elements. Conventional internal latent image-forming emulsions and photographic elements are illustrated by U.S. Patents 2,592,250; 3,206,313; 3,317,322; 3,761,276; 3,767,413; ₃,979,213 and 3,367,778.

[0014] Particularly preferred internal latent image-forming emulsions are those containing converted-halide grains, as described in U.S. Patent 2,592,250. The term "converted-halide silver halide grains" is employed herein as a recognized word of art denoting silver halide grains prepared by forming an emulsion of silver salt grains comprised of a silver salt more soluble in water than silver bromide, and "converting" at least a portion of such grains to silver bromide or silver bromoiodide salts. The preferred converted-halide silver halide grains employed in the practice of this invention have a halide content of-at least 50 mole percent, most preferably at least 80 mole percent, bromide and up to 10 mole percent, most preferably less than 5 mole percent, iodide, any remaining halide being chloride. Especially good results are obtained with converted-halide silver halide grains containing about 93 mole percent bromide and about 10 mole percent chloride.

[0015] The silver halide grains can be internally fogged as they are formed, but it is generally more convenient to expose the emulsions or elements with light after they are formed. In converting the conventional internal latent image-forming elements to internally fogged elements by light exposure it is preferred that exposures be sufficient to produce a maximum density when the elements are thereafter developed in an internal developer, such as in Reference Internal Developer A as described above. The internal latent image-forming elements are substantially free of surface fog, and, since they form internal latent images upon exposure, after light exposure and processing in a surface developer, such as Reference Surface Developer B as described above, they yield densities substantially below the preferred 0.1 minimum density levels. The foregoing density characteristics are, of course, those which the emulsion layers exhibit prior to ultrasonic exposure.

[0016] One or more photographic hydrophilic vehicle materials are present in combination with the internally fogged silver halide grains to form the emulsion layer or layers of the elements. The vehicles are also present in layers, if any, which overlie the emulsion layers. The vehicles perform the various functions conventionally performed in photographic elements-- e.g., peptizing and binding. The vehicles employed are those which are penetrable by conventional aqueous photographic processing liquids, such as developers. As employed in the practice of this invention the vehicles perform the additional function of acting a. a barrier to impede diffusion of solute to the internally fogged silver halide grains in the absence of ultrasound.

[0017] It is generally preferred to employ hydrophilic colloids alone or in combination with other materials as vehicles. Suitable hydrophilic materials include both naturally occurring substances such as proteins, protein derivatives, cellulose derivatives--e.g., cellulose esters, gelatin--e.g., alkali-treated gelatin (cattle bone or hide gelatin) or acid-treated gelatin (pigskin gelatin), gelatin derivatives--e.g., acetylated gelatin, phthalated gelatin and the like, polysaccharides such as dextran, gum arabic, zein, casein, pectin, collagen derivatives, collodion, agar-agar, arrowroot, albumin and the like.

[0018] The element layers can also contain alone or in combination with hydrophilic water permeable colloids as vehicles or vehicle extenders (e.g., in the form of latices), synthetic polymeric peptizers, carriers and/ or binders such as poly(vinyl lactams), acrylamide polymers, polyvinyl alcohol and its derivatives, polyvinyl acetals, polymers of alkyl and sulfoalkyl acrylates and methacrylates, hydrolyzed polyvinyl acetates, polyamides, polyvinyl pyridine, acrylic acid polymers, maleic anhydride copolymers, polyalkylene oxides, methacrylamide copolymers, polyvinyl oxazoli- dinones, maleic acid copolymers, vinylamine copolymers, methacrylic acid copolymers, acryloyloxyalkylsulfonic acid copolymers, sulfoalkylacrylamide copolymers, polyalkyleneimine copolymers, polyamines,.N,N-dialkylaminoalkyl acrylates, vinyl imidazole copolymers, vinyl sulfide copolymers, halogenated styrene polymers, amineacrylamide polymers, polypeptides and the like.

[0019] It is a significant advantage of this process that the internally fogged silver halide elements in their preferred form can be handled in room light and that nc requirement of either exposing the elements to light or protecting the elements from ordinary room light, such as incandescent lighting, is imposed on the process. Thus, there is nc requirement for darkroom processing, nor is there any required light exposure step to complicate subsequent processing steps or the apparatus employed in their performance.

[0020] Although the foregoing discussion has been in terms of light exposure, it is appreciated that these comments are generally applicable to forms of electromagnetic radiation conventionally employed in the exposure of photographic elements. For example, in addition to light within the visible spectrum or within a selected portion thereof, other wavelengths of electromagnetic radiation, such as ultraviolet light, infrared radiation, X-rays and gamma rays, are particularly contemplated for converting internal latent image-forming silver halide photographic elements into internally fogged elements.

[0021] The internally fogged silver halide element is in contact during ultrasonic exposure with a transport liquid, which serves two distinct functions. First, the transport liquid acts as a medium for the transmission of ultrasound. Liquids transmit ultrasonic energy more efficiently (that is, with less attenuation) than gaseous media. Second, the transport liquid serves as a reservoir for a solute which can be initially present in the internally fogged photographic element or the transport liquid.

[0022] The transport liquid is related to the internally fogged emulsion layer(s) of the element so that a diffusion path for the solute is available between the transport liquid and the internally fogged emulsion layer(s). This can be accomplished by relating the transport liquid and the internally fogged element i:. any conventional manner of bringing a developer solution into contact with a photographic element for purposes of photographic processing. In a simple form the transport liquid can be spread on the emulsion coated surface of the element by coating, or the element can be immersed in the transport liquid.

[0023] The specific choice of a transport liquid to be placed in contact with the internally fogged element will be influenced, of course, by the specific solute chosen. Where the solute is being transported in ionized form, it is preferred that the transport liquid be a polar solvent. Water is a preferred polar solvent for use in the practice of this process. However, any polar solvent or combination of polar solvents known to be compatible with the elements and solute can be employed. Exemplary useful polar solvents in addition to water include water-miscible alcohols, ketones and amides (e.g., acetone, phenol, ethyl alcohol, methyl alcohol, iospropyl alcohol, ethylene glycol, N,N-dimethylacetamide, and methyl ethyl ketone), tetrahydrofuran, N-methyl-2-pyrrolidone, dimethylsulfoxide and mixtures of the above, with or without water. Generally any transport liquid can be employed which is chemically compatible with the solute and the internally fogged element.

[0024] Any solute can be employed in the practice of this invention which, following contact with the internally fogged silver halide grains, is capable of rendering them developable in a surface developer, such as Reference Surface Developer B. Iodide ions are particularly effective in rendering internally fogged silver halide grains developable in a surface developer. It is known that silver iodide has a solubility product constant which is approximately two orders of magnitude less than that of silver bromide and approximately four orders of magnitude less than that of silver chloride. On the other hand, photographic silver halide emulsions conventionally contain less than about 20 (typically less than 10) mole percent silver iodide, based on total silver halide. What is believed to occur when a photographic silver halide is brought into contact with iodide ions in the presence of a transport liquid is that the iodide ions displace the bromide and/or chloride atoms in the silver halide crystal lattice so that the much less soluble silver iodide is formed. The iodide ions, being much larger than the bromide and/or chloride atoms which they displace in the crystal lattice, disrupt the crystal structure to the extent of opening the interior of the silver halide grains to contact with a surface developer. Any convenient source of iodide ions can be employed as a solute in the practice of this process. Where the transport liquid is water or an aqueous medium, water soluble iodide salts can be employed, such as alkali iodide e.g., sodium iodide, potassium iodide and lithium iodide. While suitable iodide concentrations under varied conditions can be readily ascertained, as described below, it is typically preferred to employ iodide ion concentrations of from about 100 to 1000, preferably 200 to 800, milligrams per liter of transport liquid. If the iodide solute is incorporated in the element, it should be coated in a layer separate from the internally fogged silver halide emulsion layer.

[0025] Known silver halide solvents can also be employed as solutes in the practice of this process. Water soluble thiosulfates constitute a specifically preferred class of silver halide solvents. Water soluble thiosulfates, particularly ammonium and alkali metal thiosulfates, such as sodium and potassium thiosulfates, are commonly incorporated in silver halide developers to provide the capability of developing internal latent images. Thiosulfate concentrations in the transport liquid are preferred corresponding to the concentrations in which thiosulfates are conventionally incorporated in internal silver halide developers.

[0026] Another class of silver halide solvents are water soluble sulfur-containing compounds of the type which have been conventionally employed as ripening agents when employed in the formation of silver halide emulsions. Such sulfur-containing compounds include water-soluble thioethers and thiocyanates.

[0027] Conventional thioethers, such as those disclosed in U.S. Patent 3,271,157 can be employed. Certain of the preferred organic thioether silver halide solvents can be represented by the formulas:



and

wherein: r and m are integers of 0 to 4; n is an integer of 1 to 4; p and q are integers of 0 to 3; X is an oxygen atom (-0-), a sulfur atom (-S-), a carbamyl radical

a carbonyl radical

)r a carbonyl radical

or R and R' are ethylene oxide radicals (-O-CH₂CH₂-); Q and Z are hydroxy radicals (-OH), carboxy radicals, or alkoxy radicals (-O-alkyl) wherein the alkyl group has 1 to 5 carbon atoms; and Q and Z can also be substituents described for X linked to form a cyclic compound

[0028] Preferred organic thioether silver halide solvents include compounds represented by the formulas:









and

wherein: r is an integer of 1 to 3; s is an integer of 1 to 2; R² is an alkylene radical having 1 to 5 carbon atoms and is preferably ethylene (-CH₂CH₂-); R³ is an alkyl radical having 1 to 5 carbon atoms and is preferably ethyl; and R⁴ is an alkylene radical having 1 to 5 carbon atoms and is preferably methylene (-CH₂-).

[0029] As an alternative to thioether silver halide solvents, thiocyanate salts can be used, such as alkali metal, most commonly potassium, and ammonium thiocyanate salts. Conventional thiocyanates can be employed, such as those disclosed in U.S. Patents 2,222,264, 2,448,534 and 3,320,069, as ripening agents.

[0030] Another useful class of silver halide solvents are pyridinium salts, such as those disclosed in U.S. Patent 2,648,604. The preferred pyridinium salts to be employed can be represented by the following general formula:

wherein D represents the atoms necessary to complete an unsubstituted pyridinium nucleus, an alkoxy-substituted pyridinium nucleus, e.g., a 2-methoxy-, 3-methoxy-, 4-methoxy-, 2-ethoxy-, 3-ethoxy-, 2,4-dimeth- oxy-, 2,4-diethoxy-, 2,5-diethcxy-, or 3,5-diethoxy- pyridinium nucleus; a picolinium nucleus, e.g., a 4-methyl-, 2-methyl-, or 3-methyl-pyridinium nucleus; a lutidinium nucleus, e.g., a 2,3-dimethyl-, 2,4-dimethyl-, 2,5-dimethyl-, 2,6-dimethyl-, 3,4-dimethyl-, 3,5-dimethyl-, 2-ethyl-, 3-ethyl- or 4-ethyl-pyridinium nucleus; a collidinium nucleus, e.g., a 2-propyl-, 2-isopropyl-, 4-methyl-2-ethyl-, 4-methyl-3-ethyl-, 2-methyl-4-ethyl-, 2-methyl-5-ethyl-, 2-methyl-6-ethyl-, 2,3,4-trimethyl-, or 2,3,6-trimethyl-pyridinium nucleus, or a parvolinium nucleus, e.g., a 2-butyl-, 2-isobutyl-, 3,5-dimethyl-2-ethyl-, 2,6-dimethyl-3-ethyl-, 2,6-dimethyl-4-ethyl-, 2,4-diethyl- or 3,4-diethyl- pyridinium nucleus; wherein R is a short chain aliphatic radical having not more than 5 carbon atoms, such as alkyl, e.g., methyl, ethyl, propyl, butyl or amyl; chloro-or bromoalkyl, e.g., β-chloroethyl, β-bromoethyl, γ-chloropropyl or y-bromopropyl; hydroxyalkyl, e.g., 6-hydroxyethyl, β-hydroxypropyl, or β,γ-dihydroxypropyl, carboxymethyl; carbalkoxymethyl, e.g., carbomethoxymethyl, carbethcxymethyl or carbo- propoxymethyl, carboxamidomethyl; N-substituted carboxamidomethyl, e.g., N,N-dimethylcarboxamidomethyl; alkoxyalkyl, e.g., methoxymethyl, ethoxymethyl, ethoxyethyl or propoxymethyl; and wherein X represents an anion such as chloride, bromide thiocyanate, methylsulfate and thiocyanate.

[0031] In addition to the use of thioethers, thiosulfates, thiocyanates and pyridinium salts as silver halide solvents, soluble sulfite salts, such as alkali sulfite salts, in the presence of ultrasound are useful solvents for high chloride silver halide grains. Higher chloride silver halide grains are those which are greater than 50 mole percent chloride, based on total halide. However, sulfite solutes are not effective solvents for silver bromide and silver bromoiodide grains.

[0032] The internally fogged silver halide element, in contact with the transport liquid and solute, is imagewise exposed to ultrasonic radiation. This can be accomplished using any conventional sonic camera which is capable of impinging ultrasonic radiation on the element as an image receptor. In such a sonic camera a sonic source or transducer (i.e., an emitter of ultrasonic radiation) and the element are spatially related so that the ultrasonic radiation, unless interrupted, can impinge on the silver halide emulsion layer(s) to be imagewise exposed. Between the sonic transducer and the internally fogged element is interposed any means which will imagewise modulate the ultrasonic radiation as it is received by the emulsion layer(s). In a simple form this can take the form of an apertured template which absorbs or reflects the ultrasonic radiation which strikes it and allows a portion of the ultrasonic radiation to pass through the aperture to the element. Alternatively the reflected ultrasonic radiation can be caused to impinge on the element. In a more sophisticated form the imaging means can include combinations of sonic lenses and reflectors for focusing and directing the ultrasonic radiation. In one application of this process an object whose ultrasonic modulation characteristic is desired to be recorded is placed in the sonic camera so that it intercepts ultrasonic radiation passing from the sonic transducer to the element. For example, the ultrasonoscope described ir U.S. Patent 3,765,403, can be readily adapted for use as a sonic camera in the practice of this invention merely by locating the internally fogged element in one of the water tanks so that it is impinged by the ultrasonic radiation which has passed through or been reflected by the mamma under examination.

[0033] In a simple mode of practicing this process, a single transport liquid is in contact with the sonic transducer and the internally fogged element and provides a medium for transmission of ultrasound therebetween. In an alternative form the sonic transducer can be contacted with one transport liquid and a second transport liquid can be in contact with the internally fogged element with an ultrasonically transmitting partition, such as a membrane, separating the two transport media. In still another form the solute and a first transport liquid can be entirely within the emulsion layer(s) to be imagewise exposed and a second transport liquid which is chemically compatible with the internally fogged element can be placed in contact therewith to permit ultrasonic exposure. For example, a polar solvent containing the solute can be imbibed into or coated on the emulsion layer to be exposed and then the internally fogged element immersed in a nonpolar liquid, such as cyclohexane, benzene, etc.

[0034] Except where rapid alteration of the developability as a function of contact with the transport liquid and solute prohibits, it is preferred to allow the element at least a few seconds, preferably at least 5 seconds, of contact with the transport liquid before initiating ultrasonic exposure. It is within the invention to bring the internally fogged silver halide element into contact with the transport liquid first and then later to add the solute to the transport liquid reservoir. Delaying ultrasonic exposure after initial contact with the transport liquid can be used to enhance ultrasonographic response. The optimum delay period for a particular element can be correlated to the contact period at which incipient alteration of the developability of the element is observed in the solute selection test. For some elements alteration of developability begins immediately upon contact with the transport liquid and solute, and there is no advantage to delaying the ultrasonic exposure.

[0035] Some elements, such as those having film supports, directly absorb only a very small fraction of the total ultrasonic radiation to which they are exposed, the rest passing directly through the element. Accordingly, it is possible during ultrasonic exposure to orient an internally fogged film element so that either the emulsion layer bearing surface or the film support of the element is nearest to the sonic radiation source. Also, one or a plurality of imaging emulsion layers can be coated on either or both major surfaces of the film support and concurrently exposed. Further, it is possible to stack two or more film elements so that ultrasonic radiation passes through them sequentially during exposure. Of course, where precise focusing of the ultrasonic radiation is desired, the number of film elements which will produce optimum images may be limited. By way of contrast, photographic paper supports absorb almost all of the ultrasonic imaging radiation to which they are exposed according to this process. For elements having paper supports the silver halide emulsion layer must be on the side nearest to the source of the ultrasonic radiation source. Better image quality is obtained in all instances where the emulsion-flayer is on the face of the support nearest the ultrasonic energy source.

[0036] Imagewise exposure of the internally fogged element in the sonic camera is at an intensity and for a duration which is insufficient to produce a developable image in the absence of the solute. The level of ultrasonic exposure is lower than that which has been recognized in the art to produce ultrasonic images in the absence of light or to render imagewise developable surface fogged silver halide elements. The ultrasonic imaging exposure is itself insufficient to produce a variation in the development of the internally fogged emulsion layer(s) of the element being exposed in the absence of the solute. Successful imaging is readily achieved at ultrasonic exposures below 100 watt-sec/cm2 by this process.

[0037] Just as different photographic elements exhibit marked differences in their sensitivity to electromagnetic exposure, different internally fogged elements will also exhibit different sensitivities to ultrasonic radiation. By exposing internally fogged elements to differing ultrasonic intensities and then performing the photographic processing steps intended for use, the optimum ultrasonic exposure for a given internally fogged element can be readily determined. In a manner analogous to light sensitometry using a step tablet, it is possible to expose an internally fogged element simultaneously in offset areas with an array of laterally spaced sonic transducers which are calibrated to transmit ultrasonic radiation at predetermined stepped levels of intensity. Upon photographic processing, densities produced by each transducer can be plotted against ultrasonic exposure. This generates an ultrasonic characteristic curve for the particular internally fogged element from which the optimum intensity of ultrasonic exposure can be readily determined.

[0038] The determination can be repeated using differing durations of ultrasonic exposure, if desired, although this is not usually necessary. In using photographic cameras varied shutter speeds (exposure times) and f-stop settings (exposure intensities) are available to the photographer to achieve a given exposure, since exposure is recognized to be the mathematical product of exposure time and intensity. The proposition that equal photographic exposures differing in intensity and duration produce similar photochemical response is referred to as the photographic reciprocity law, and this law is generally relied upon in photography in varying exposure times and intensities, although it is recognized that many photographic elements exhibit significant reciprocity law failure. By analogy to photography, various combinations of ultrasonographic exposures as a mathematical product can be relied upon in a general way in accordance with a reciprocity law of ultrasonic exposure which is analogous to the photographic reciprocity law.

[0039] Any ultrasonic frequency heretofore employed in ultrasonography can be applied to the practice of this process. For a given transport liquid the wavelength of the ultrasonic radiation is reciprocally related to its frequency. Since best imaging results in ultrasonography and ultrasonoscopy are recognized to be obtainable when the wavelength of the ultrasonic imaging radiation is substantially shorter than the dimension of the object or object feature to be imaged, it is generally preferred to operate at shorter wavelengths and hence higher frequencies. For example, at a frequency of 1 megahertz ultrasonic radiation transmitted in water exhibits a wavelength in the order of 1.5 millimeters. Accordingly, in obtaining ultrasono- graphs of objects or object features of 1.5 millimeters in dimension it is preferred to operate substantially above 1 megahertz, typically in the range of 2.5 to 100 megahertz. Frequencies in the order of gigahertz are known in the art and can be employed, particularly when microscopic image definition is required. The high operating frequencies are, of course, advantageous since they effectively define both large and small objects and object features, although increased absorptivity of many materials at higher frequencies requires thinner object samples. In the prior art, ultrasonic exposures of photographic elements have most typically occurred at lower frequencies in order to stimulate cavitation. This process is not similarly limited.

[0040] The ultrasonic exposure of the photographic element can be constant in intensity for the duration of expcsure or it can be varied in intensity. Pulsing of the ultrasonic exposure can be achieved by continuously modulating the intensity of exposure, preferably by interrupting ultrasonic exposure so that ultrasonic exposure is divided into separate bursts or discrete pulses. It is contemplated to employ discrete pulses wherein the duration of the pulses and the interval therebetween is less than a tenth of a second. The duration of the ultrasonic pulse and the interval between pulses can be varied independently, if desired. The minimum useful pulse and interval durations are limited only by the capabilities of the ultrasonic emitters selected for use. Naturally, as the pulses and intervals between pulses approach the frequency of the ultrasonic radiation, continuous exposure will be approached as a limit.

[0041] In one specifically contemplated form of this process the internally fogged element is contacted with the transport liquid and solute, ultrasonically imagewise exposed and then developed in a surface developer. Development preferentially occurs in ultrasonically exposed areas to produce a negative ultrasonic image. In one preferred form the transport liquid is water, and the solute is dissolved in the water or is incorporated in the element, such as in an overcoa; layer. In a specifically preferred form the internally fogged element is immersed in a bath which consists essentially of water and the solute which can be diffusing into the element during ultrasonic exposure. In an alternative form a conventional viscosity increasing agent can be added to the transport liquid, and it can be spread as a layer on the internally fogged element.

[0042] The term "surface developer" is employed in its art recognized usage to indicate developers which are capable of developing silver halide grains containing a surface latent image or surface fog, but not silver halide grains containing only an internal latent image or internal fog. The surface developers can generally utilize any of the silver halide developing agents, but the developer solution is sufficiently free of water soluble iodide salts, water soluble thiocyanates, thioethers, thiosulfates and pyridinium salts and any other solute which will disrupt or dissolve silver halide grains to avoid revealing an internal latent image or internal fog during the contemplated time of development.

[0043] In the foregoing mode of practicing this process, referred to as a sequential mode, the ultrasonic exposure occurs in the presence of a transport liquid and a solute in the absence of a silver halide developing agent, and the ultrasonically exposed element is thereafter developed in a surface developer to achieve distinct advantages. Surface development is substantially limited to those areas of the internally fogged element which have been ultrasonically exposed. This is in direct contrast to obtaining differential development of a surface fogged silver halide element as a result of imagewise ultra-sound exposure. In the latter instance silver halide development occurs in both ultrasonically exposed and background areas. In the sequential mode of practicing this process a relatively low minimum density level in unexposed areas is obtainable, since the internal fog sites within the silver halide grains are not accessible to the surface developer. Further, there is no necessity of arresting development before maximum image densities are obtained in order to avoid elevated minimum densities. Finally, it is a surprising feature of this process that development of the internally fogged element to produce a viewable image can be achieved using a surface developer. The ability of imagewise ultrasound exposure in the presence of a transport liquid and a solute to render the internally fogged element capable of being developed in a surface developer, particularly at the low ultrasonic energy levels employed, has never before been recognized as possible or achieved by those skilled in the art.

[0044] In the sequential mode the surface developer is not brought into contact with the internally fogged element until ultrasonic imagewise exposure is completed. It has been observed that a significant increase in the imaging sensitivity of this process is achieved if development follows ultrasonic exposure. Specifically, it has been observed that a significant enhancement in density differences between ultrasonically exposed and background areas can be achieved when development is delayed from 10 to 200 seconds (optimally from 15 to 50 seconds) following ultrasonic exposure at ordinary room temperature (20 to 25°C). This enhancement of the ultrasonographic image is attributed to a furtherance during the delay period of the alterations of the internally fogged element initiated by ultrasonic exposure.

[0045] In an alternative form of this process the internally fogged silver halide element is imagewise ultrasonically exposed while in contact with an internal developer. Internal developers are those capable of developing silver halide grains which contain an internal latent image or internal fog. One conventional approach of ascertaining if a developer is an internal developer is to light expose an internal latent image-forming silver halide emulsion and then to bleach the surface of silver halide grains to remove any surface fog. If the developer is capable of producing a substantial density by development of surface bleached silver halide grains, it is an internal developer. In quantitative terms, preferred internal developers are those which produce a density of at least 0.5 within 5 minutes at 25°C in a silver halide element useful in the practice of this process which has been light exposed to provide a maximum density and then bleached for 5 minutes at 25°C in a 0.3 percent aqueous solution of potassium ferricyanide. Conversely, developers which fail to produce a density of at least 0.5, preferably 0.1, are preferred surface developers. Among the advantages of imagewise ultrasonic exposure in the presence of an internal developer are that imaging can be readily achieved with minimal ultrasonic energy levels and only a single processing solution is employed for both ultrasonic exposure and development. However, care must be exercised to avoid extended contact of the element with the internal developer, since this can result in background fog.

[0046] In another sequential form of this process the internally fogged silver halide element is imagewise ultrasonically exposed in a silver halide solvent as described above, such as a thioether, thiosulfate, thiocyanate or, in the case of high chloride silver halide grains, a sulfite, and in the absence of a developer. By increasing the solvent action on the silver halide grains being ultrasonically exposed, such as by using higher ultrasonic energy levels, longer exposure periods, higher solute concentrations or some combination of these, the silver halide grains in ultrasonically exposed areas can be substantially entirely dissolved. In areas where ultrasonic exposure does not occur the silver halide grains may be unaffected by the silver halide solvent or, preferably, the silver halide grains can be sufficiently modified by the solvent that they become developable in a surface developer. In the former case the silver halide grains are thereafter developed in an internal developer while in the latter case the silver halide grains can thereafter be developed in either a surface or an internal developer. Development produces little or no density in ultrasonically exposed areas, since the silver halide in exposed areas has been dissolved and removed, whereas the developer readily develops the internally fobbed silver halide grains in the areas which are not ultrasonically exposed. The result is a reversal or positive image, that is, a maximum density is produced in areas of the elements which are not ultrasonically exposed. By carefully limiting both the degree of silver halide dissolution in the ultrasonic exposure step and the development step, it is possible alternatively to produce a negative image by this process mode, but such a form of the ion is not preferred, since high background densities are to be expected.

[0047] This process can be practiced with any conventional surface or internal developer. The surface developers can be converted to internal developers by incorporating silver halide solvents, such as thioethers, thiosulfates and thiocyanates, water soluble iodide salts or, in the case of high chloride silver halides, water soluble sulfites in the solute concentrations disclosed above or as ascertained by the solute selection test procedures.

[0048] It should be pointed out that while ultrasonic exposure times can be quite low, in the order of a few seconds or less, once the internal fog within the silver halide grains has been revealed by the action of ultrasonic exposure acting in conjunction with the transport liquid and solute, the rates of development are those that would.be expected from a knowledge of photographic development procedures. Accordingly, in the modes of ultrasonic exposure in the presence of a developer, it is apparent that ultrasonic exposure will be completed well before optimum development of the elements has been achieved. Because ultrasonic exposure periods will ordinarily be so low as to be negligible in comparison with total development times, development periods in both the sequential and concurrent exposure- development modes will typically be those experienced in conventional photographic development, typically from 30 seconds to 10 minutes, most commonly from 1 to 5 minutes.

[0049] An optimum imaging response for any specific system described above can be achieved by routine adjustments. For example, the solubility of silver chloride is higher than that of silver bromide which is in turn higher than that of silver iodide, and this permits weaker silver halide solvents and/cr lower solvent concentrations to be employed with silver chlorides than with silver bromides and silver bromo- iodides. In addition to the variance in the activity levels of silver halide solvents, there is a wide variance in the activity levels of silver halide solvents. The choice and concentration levels of the silver halide solvents are also influenced by whether a negative ultrasonographic image is being formed, in which instance the silver halide solvent acts in ultrasonically exposed areas to reveal the internal fog sites in the silver halide grains, or a positive ultrasonographic image is being formed, in which instance the solvent acts to dissolve the silver halide grains in exposed areas. For negative-working ultrasonographic imaging it is preferred to employ silver halide solvents such as thioethers, thiosulfates, thiocyanates and pyridinium salts of the type described in concentrations of from 0.1 to 30 grams per liter of transport liquid, with concentrations of from 0.5 to 5.0 grams per liter being specifically preferred for thiosulfates and concentrations of from 5 to 15 grams per liter being specifically preferred for thiocyanates. Higher concentration levels can be employed in producing positive ultrasonographic images with these solvents. For sulfite solutes negative ultrasonographic images in silver chloride emulsions can be obtained with preferred concentrations in the range of from 10 to 50 grams per liter, while positive ultrasonographic images can .be obtained with preferred concentrations in the range of from 80 to 100 grams per liter.

[0050] The preferred solute concentration ranges set forth above assume conventional ratios of the internally fogged silver halide grains to vehicles, typically in the range of from 1:2 to 2:1, on a weight basis. Since the vehicle provides an impedance to the diffusion of the solute, it is apparent that adjustment of the proportion of the vehicle and its permeability, as by hardening, can be relied upon to control the diffusion rate of the solute, or, conversely, the concentration of the solute can be varied to adjust the rate of response of a selected internally fogged element. For example, if an internally fogged element responds too rapidly to the solute for convenient handling, its rate of response can be decreased merely by overcoating the emulsion layer with a vehicle overcoat or by reducing the concentration of the solute in the transport liquid.

[0051] A preferred negative-working system will, in the absence of ultrasound, within a period of from 10 seconds to 10 hours of contact with the transport liquid containing the solute cause the internally fogged element to produce a density of at least 0.5, preferably at least 1.0, when thereafter developed in a surface developer, such as Reference Surface Developer B, for 5 minutes at 25°C. If the density is achieved in less than 10 seconds in the absence of ultrasound, reproducible imaging will be difficult without obtaining high background densities or without employing high speed transport equipment for bringing the internally fogged element into and out of contact with the solute, although this is, of course, possible. On the other hand, if a density of at least 0.5 is not obtained within 10 hours following contact of the solute with the internally fogged element, the process will be unattractively slow when ultrasound is employed at lower power levels, such as-are preferred in the practice of this process.

[0052] Similarly, a preferred positive-working system will, in the absence of ultrasound, within a period of from 10 seconds to 10 hours of contact with the transport liquid containing the solute cause the internally fogged element to produce a density of at least 0.5 less, preferably at least 1.0 less, when thereafter developed in an internal developer, such as Reference Internal Developer A, for 5 minutes at 25°C, than the density produced in an identical element which is otherwise similarly processed, but which is not placed in contact with the transport liquid containing the solute.

[0053] It is recognized that in at least some instances identical elements can be used to produce either positive or negative ultrasonographic images, merely by adjusting silver halide solvent concentrations and/or ultrasonic exposure levels, and the very same solvent concentrations and ultrasonic exposure levels can produce either positive or negative ultrasonographic images by varying the silver halide and/or vehicle of the internally fogged elements being employed.

[0054] It is specifically recognized that the internally fogged elements employed, particularly the silver halide emulsion layers thereof employed in imaging, can be protected against the production of surface fog. Conventional antifoggants and stabilizers, which can be used alone or in combination include the thiazolium salts, azaindenes, mercury salts, urazoles, sulfocate- chols, oximes, nitron, nitroindazoles, mercaptotetrazoles, polyvalent metal salts, thiuronium salts, and palladium, platinum and gold salts.

[0055] The viewable image produced in each of the various modes of practicing this process can be either a silver image, a dye image or a combination of both. Dye images can be formed through the use _of a color developer composition and color couplers, for example. The color couplers can be incorporated in either the developer composition, as in the case of mobile couplers, or in the ultrasonographic element, as in the case of ballasted couplers. Ballasted couplers .are typically incorporated directly in the imaging silver halide emulsion layer or in a layer adjacent thereto. Generally any color image-forming approach which makes use of a silver image can be employed in the practice of my process. Color materials are discussed, for example, in paragraph XXII, Product Licensing Index, Vol. 92, December 1971, publication 9232. Both Product Licensing Index and Research Disclcsure are published by Industrial Opportunities, Homewell, Havant Hampshire, P09 iEF, United Kingdom.

[0056] It is specifically contemplated that the elements can produce dye images through the selective removal of dyes. Negative or positive dye images can be produced by the immobilization or mobilization of incorporated color-providing substances as a function of exposure and development, as illustrated by U.S. Patents 2,543,691; 3,227,552; 3,443,940; 3,549,364; 3,620,730; 3,730,718; 3,923,510; 4,052,214; and 4,076,529; and U.K. Patents 1,456,413; 1,479,739; 1,475,265 and 1,471,752.

[0057] The internally fogged elements can contain hardeners for the hydrophilic colloid layers, as described in paragraph VII plasticizers, lubricants, coating aids and matting agents, as described in paragraphs XI, XII and XIII Product Licensing Index, publication 9232, cited above.

[0058] The photographic layers, including the silver halide emulsion layers and other layers of the elements can be coated on a wide variety of supports. Typical supports include cellulose nitrate film, cellulose acetate film, poly(ethylene terephthalate)film, polycarbonate film and related films or resinous materials, as well as glass, paper, metal and the like. Typically, a flexible support is employed, especially a paper support, which can be partially acetylated or coated with baryta and/or an alpha-olefin polymer, particularly a polymer of an alpha-clefin containing 2 to 10 carbon atoms such as polyethylene, polypropylene, ethylenebutene copolymers and the like.

[0059] Well known processing techniques and procedures can be employed. For example, the pH of the developer can be reduced to stop development, as by the use of a conventional stop bath. Where a surface developer is employed, pH reduction to stop development can be readily omitted without adverse effect in most instances. Where a dye image is formed, the silver image in the photographic element can be removed by bleaching or blixing. While fixing of the silver halide can be undertaken, the lack of light sensitivity of the silver halide in most instances renders this step unnecessary. Processing formulations and techniques are described in L. F. Mason, Photographic Processing Chemistry, Focal Press, London, 1966; Processing Chemicals and Formulas, Publication J-1, Eastman Kodak Company, 1973; Photo-Lab Index, Morgan and Morgan, Inc., Dobbs Ferry, New York, 1977, and Neblette's Handbook of Photography and Reprography - Materials, Processes and Systems, Van-Nostrand Reinhold Company, 7th Ed., 1977.

[0060] Included among the processing methods are web processing, as illustrated by U.S. Patent 3,179,517; stabilization processing, as illustrated by U.S. Patents 3,220,839, 3,647,453 and 3,615,511 and U.K. Patent 1,258,906; monobath processing and described in Haist, Monobath Manual, Morgan and Morgan, Inc., 1966, U.S. Patents 3,240,603, 3,615,513, 3,628,955 and 3,723,126; infectious development, as illustrated by . U.S. Patents 3,294,537, 3,600,174, 3,615,519, 3,615,524 3,516,830, 3,615,488, 3,625,689 and 3,708,303, and U.K. Patent 1,273,030; hardening development, as illustrated by U.S. Patent 3,232,761; roller transport processing, as illustrated by U.S. Patents 3,025,779, 3,515,556, 3,573,914 and 3,647,459, and U.K. Patent 1,269,268; alkaline vapor processing, as illustrated by Product Licensing Index, Vol. 97, May 1972, Item 9711, U.S. Patents 3,816,136 and 3,985,564; metal ion development as illustrated by Price, Photographic Science and Engineering, Vol. 19, Number 5, 1975, pp. 283-287 and Vought, Research Disclosure, Vol. 150, October 1976, Item 15034; reversal processing, as illustrated by U.S. Patent 3,576,633; and surface application processing, as illustrated by U.S. Patent 3,418,132.

[0061] Dye images which correspond to the silver halide rendered selectively developable by imagewise exposure, typically negative dye images, can be produced by processing, as illustrated by the Kodacolor C-22 the Kodak Flexicolor C-41 and the Agfacolor processes described in British Journal of Photography Annual, 1977, pp. 201-205. The photographic elements can also be processed by the Kodak Ektaprint-3 and -300 processes as described in Kodak Color Dataguide, 5th Ed., 1975, pp. 18-19, and the Agfa color process as described in British Journal of Photography Annual, 1977, pp. 205-206.

[0062] The photographic elements can be processed in the presence of reducible species, such as transition metal ion complexes (e.g. cobalt (III) and ruthenium (III) complexes containing amine and/or amine ligands) and percxy compounds (e.g. hydrogen peroxide and alkali metal perborates and perearbonates).

[0063] Dye images can be formed or amplified by processes which employ in combination with a dye-image- generating reducing agent an inert transition metal complex oxidizing agent, as illustrated by U.S. Patents ₃,₇48,138; ₃,826,652; 3,862,842; 3.989,526 and 3,765,891, and/or a peroxide oxidizing agent, as illustrated by U.S. Patent 3,674,490, Research Disclosure, Vol. 116, December 1973, Item 11660, and Bissonette, Research Disclosure, Vol. 148, August 1976, Items 14836, 14846 and 14847. The photographic elements can be particularly adapted to Form dye images by such processes, as illustrated by U.S. Patents 3,822,129; 3,834,907; 3,847,619; 3,902,905 and 3,904,413.

[0064] The presence of transition metal ion complexes can accelerate silver halide development, as illustrated by U.S. Patents 3,748,138; 3,901,712 and 3,964,912; can bleach silver images, as illustrated by Bissonette U.S. Patent 3,923,511 and Research Disclosure, Item 14846, and can be employed to form tanned colloid images, as illustrated by U.S. Patents 3,856,524 and 3,862,855.

[0065] The developers and elements can contain organic or inorganic developing agents or mixtures thereof. Examples of useful organic developing agents include hydroquinones, catechols, aminophenols, pyrazolidones, phenylenediamines, tetrahydroquinolines, bis(pyridone)-amines, cycloalkenones, pyrimidines, reductones, and coumarins. Useful inorganic developing agents include compounds of a metal having at least two distinct valence states which is capable of reducing ionic silver to metallic silver. Such metals include iron, titanium, vanadium and chromium, and the metal compounds employed are typically complexes with organic compounds such as polycarboxylic acids or aminopolycarboxylic acids. Particularly useful developing agents include the iodohydroquinones of U.S. Patent 3,297,445, the amino hydroxy cycloalkenones of U.S. Patent 3,690,872, the 5-hydroxy and 5-amino pyrimidines of U.S. Patent 3,672,891, the N-acyl derivatives of p-aminophenols of British Patent 1,045,303, the 2-acyl and 3-acyl derivatives of 3-pyrazolidones of British Patent 1,023,701, the 2-hydroxyalkyl and 2-aminoalkyl-3-pyrazolidones of U.S. Patent 3,241,967, the anhydro dihydro reductones of U.S. Patent 3,672,896, and the 6-hydroxy and 6-amino coumarins of U.S. Patent 3,615,521. Advantageous results can be obtained with combinations of organic and inorganic developing agents as described in Vought, Research Disclosure, Vol. 150, October 1976, Item 15034, and with combinations of different types of organic developing agents such as the combination of anhydro dihydro amino reductones and aminomethyl hydroquinones of U.S. Patent 3,666,457 and the combination of ascorbic acid and 3-pyrazolidone of British Patent 1,281,516. Developing agents can be incorporated in the elements in the form of precursors. Examples of such precursors include the halogenated acyl hydroquinones of U.S. Patent 3,246,988, the N-acyl derivatives of aminophenols of U.S. Patent 3,291,609, the reaction products of a catechol or hydroquinone with a metal described in U.S. Patent 3,295,978, the quinhydrone dyes of U.S. Patent 3,565,627, the cyclohex-2-ene-1,4-diones and cyclohex-2-ene-1-one-4-monoketals of U.S. Patent 3,586,506, and the Schiff bases of p-phenylenediamines of Pupo et al, Research Disclosure, Vol. 151, November 1976, Item 15159.

[0066] The developing agents can be present in one or more hydrophilic colloid layers of the elements, such as a silver halide emulsion layer or a layer adjacent the emulsion layer. The developing agent can be added to the layer in the form of a dispersion with a film- forming polymer in a water immiscible solvent, as illustrated by U.S. Patent 3,518,088, or as a dispersion with a polymer latex, as illustrated by Research Disclosure, _Vol. 159, July 1977, Item 15930, and Research Disclosure, Vol, 148, August 1976, Item 14850.

[0067] The elements and developers can contain development modifiers either to accelerate or restrain development.

[0068] Development accelerators of the poly(alkylene oxide) type can be used. Representative development accelerators additionally comprise carboxylic and sulfonic acid compounds and their salts, aliphatic amines, carbamates, adducts of a thioamine with an aldehyde, polyamines, polyamides, polyesters, aminophenols, polyhydroxybenzenes, thioethers and thioamides, poly(vinyl lactams), poly(N-vinyl-2-oxaolidone), protamine sulfate, pyrazolidones, dihydropyridine compounds, hydroxyalkyl ether derivatives of starch, sulfite ester polymers, bis-sulfonyl alkanes, 1,4-thiazines and thiocarbamate. Representative development accelerators also comprise cationic compounds, disulfides, imidazole derivatives, inorganic salts, surfactants, thiazolidines and triazoles.

[0069] Representatives of development restrainers that can be used include cationic compounds, esters, lactams, mercaptans and thiones, polypeptides, poly(alkylene oxide) derivatives, sulfoxides, thiazoles, diazcles, triazoles and imidazoles.

[0070] It is contemplated that the ultrasonic exposure, development and other photographic processing steps of this process can be practiced within the temperature ranges conventionally employed in photography. The elements can be washed to remove solute after ultrasonic exposure and before development, if desired, in the sequential modes of practicing this invention.

[0071] The invention is further illustrated by the following examples:

Example 1

[0072] A converted-halide gelatino silver bromochloride emulsion (91 mole percent bromide, 9 mole percent chloride based on total halide), prepared according to Example 1 of U.S. Patent 2,592,250, was internally light fogged and coated on a polyester film support to obtain silver coverage of 3.2 g/m² and gelatin coverage of ₃.₂ g_/m²_.

[0073] The resulting ultrasonographic element was divided into identical strips for separate exposure in an j ultrasonic sensitometer.

[0074] The ultrasonic sensitometer was made up of a rectangular plastic vessel open at its top and adapted to contain a liquid reservoir. Arranged along the bottom wall of the vessel were seven identical ultrasonic transducers. The ultrasonic transducers each presented a circular emitting surface of 0.785 square centimeters, as viewed from above, and were arranged in a row, adjacent transducers being separated by 2.4 cm. The emitting surfaces of the transducers were in contact with the liquid in the reservoir. The ultrasonic frequency supplied to the transducers was 5 megahertz. Each strip to be tested was immersed in the reservoir just beneath its surface and held spaced from the transducers by about 15.0 cm using a suitable clamp to hold the strip flat and in position.

[0075] Six strips of the ultrasonographic element were immersed in the reservoir for 15 seconds before ultrasonic exposure, exposed imagewise while immersed to ultrasonic energy for 10 seconds at 2.5 watts/cm² and then left immersed for 2 minutes. Kodak Developer D-19 modified to concentrations of potassium iodide of 0, 50, 100, 125, 150 and 175 mg potassium iodide per liter of developer was used as the liquid in the reservoir. For potassium iodide concentrations of up to 100 mg per liter of developer, the minimum density in background areas remained constant at a value of approximately 0.1 density unit. In image areas a sharp increase in density was observed at potassium iodide concentrations above 50 mg potassium iodide per liter of developer. At a concentration of 100 mg of potassium iodide per liter, the maximum density was approximately 1.4 with a minimum density of approximately 0.1, and at a concentration of 175 mg potassium iodide per liter the density was approximately 3.9 with a minimum density of approximately 1.2.

[0076] The procedure above was repeated using two identical strips, but the strips were immersed for 10 seconds prior to ultrasonic exposure, exposed for 10 seconds and left immersed for 2 minutes. The strips were processed in Kodak Developer D-19 modified to contain potassium iodide of 100 and 125 mg potassium iodide per liter of developer, respectively. In Figure 1, Curve A shows the negative ultrasonographic characteristic curve obtained with the lower KI concentration and Curve B shows the corresponding curve for the higher KI concentration.

[0077] Six identical strips, without prior ultrasonic exposure, were processed in Kodak Developer D-19 modified to contain potassium iodide concentration of 100 mg of potassium iodide per liter of developer, at increasing immersion times of 1, 2, 3, 4, 5 and 6 minutes, respectively, at 25°C. Figure 2 shows the curve obtained by plotting density versus immersion time in seconds.

Example 2

[0078] Two strips of the ultrasonographic element described in Example 1 were exposed in the ultrasonic sensitometer. The liquid reservoir was filled with water. Each strip was immersed in the reservoir for 10 seconds before ultrasonic exposure. Exposure was to pulsed ultrasonic energy of 10^-6 second pulse density and 10 second intervals between pulses. The first strip was exposed for 10 seconds with a power output of the seven transducers at the film plane of 35, 8.9, 2.2, 0.55, 0.25, 0.08 and 0.031 watts/cm². The second strip was exposed for 30 seconds at twice the transducer power output used to expose the first strip. Both strips were left immersed for sixty seconds after exposure. Both strips were processed in Kodak Developer D-19 for 3 minutes, fixed, washed and dried. The processed strips were clear and transparent. No images were present.

[0079] Using two additional strips the above procedure was repeated, except as specifically noted. The water in the reservoir contained 400 mg per liter potassium iodide. The strips were imagewise exposed to ultrasonic energy for 30 seconds and left immersed for 40 seconds. The power output transducers for the third strip was the same as for the first strip. The power output of the transducers for the fourth strip was reduced by half as compared to the exposure of the first strip. High density regions corresponding to all seven transducers could be discerned in the third strip. Six regions corresponding to the higher powered transducers could be visually detected on the fourth strip. The size and density of each region on the fourth strip was less than the corresponding one on the third strip. A moderate background density was obtained, which was the same in both strips. Figure 3 is a plot of density vs. peak ultrasonic intensity (in mw/cm²) for the third and fourth strips.

Example 3

[0080] Twelve strips of the ultrasonographic-element of Example 1 were used in this example. They were exposed as in Example 2 in the reservoir containing water plus potassium iodide at varying concentrations. Total ultrasonic exposure was 10⁵ pulses so that the ultrasonic exposure was the same for all strips. Power output of the transducers was the same as for the first strip of Example 2. Besides the concentration of potassium iodide, only the length of time the strips were left immersed after exposure was varied. Table I below shows the variations in exposure conditions for the strips, numbered 1 to 12. The strips were processed as in Example 2.

[0081] As shown in Figure 4, image density increased with increasing iodide ion concentration and to a lesser degree with increasing immersion time after exposure. Background density also increased with increasing iodide ion concentration and with increasing immersion time after exposure. The gain in image density generally was less than the gain in background density with increasing immersion time so that in all four concentration series, the best image descrimination was obtained with the shortest immersion time after exposure. In this series, the 400 mg/l KI bath gave the greatest image descrimination.

Example

[0082] Two strips A and B of the ultrasonographic element of Example 1 were exposed and processed similarly as the third strip in Example 2, except that exposure was carried out in water plus potassium thiocyanate in the reservoir of the ultrasonic sensitometer. The concentration of the thiocyanate was 10 g/l. The strips were exposed to ultrasonic energy and left immersed after exposure for the times shown below in Table II. The characteristic curves are shown in Figure 5. Good ultrasonic negative images were produced.

[0083] Two strips C and D were exposed as above in the reservoir containing dissolved potassium thiocyanate (20 g/1) and were processed in Kodak Developer D-19. One strip was removed immediately after exposure and the other was left immersed for 30 seconds following ultrasonic exposure, as shown below in Table II. The characteristic curves are shown in Figure 5.

[0084] 

Example 5

[0085] Experiments similar to those of Example 4 were conducted to illustrate regions with ultrasonic exposure using an aqueous potassium thiosulfate solution in the reservoir. At concentrations of 1.25 to 2.50 g/l of thiosulfate, ultrasonic exposures were made using the same transducer power levels as for the third strip of Example 2 with ultrasonic exposure for 30 seconds. The strips were processed in Kodak Developer D-19 for three minutes, fixed, washed and dried. An ultrasonic characteristic curve was obtained exhibiting acceptable maximum densities and low minimum densities.

Example 6

[0086] Figure 6 shows ultrasonic characteristic curves for two strips of the ultrasonographic element of Example 1 exposed similarly as the third strip in Example 2, except that the strips were exposed in an aqueous potassium iodide solution (400 mg/1) and processed in Kodak Developer D-19 for three minutes. Both strips were immersed for 10 seconds before exposure, exposed to pulsed ultrasonic energy of 10^-6 second pulse duration, 10^-5 second intervals between pulses and were left immersed for 60 seconds after exposure. The first strip (A) was given 10 pulses (1 second total exposure) and the second strip (B) was given 10⁵ pulses (10 seconds total ultrasonic exposure). The greater maximum density was obtained on the second strip.

Example 7

[0087] A 0.68 micron silver chloride core-shell emulsion was coated on a polymeric film support to achieve silver coverage of 2.5 g/m² and gelatin ccver- age of 4.3 g/m². Strips of the coating were ultrasonically exposed and developed under varying conditions. Exposure was carried out in the ultrasonic sensitometer of Example 1. Actual exposures in this example were to higher power outputs at 400, 200, 110, 40, 25, 8 and 2.7 watts/cm2 or lower power outputs at 80, 25, 10, 4, 2.2, .75 and .27 watts/cm2.

[0088] Eight strips of the ultrasonographic element were exposed to pulsed ultrasonic energy (10^-6 pulse width, 10 pulse period and 10⁵ pulses) in a solution of potassium sulfite (K₂SO₃) in water and developed as shown below in Table III. Development time was six minutes at 20°C. The coatings were then fixed, washed and dried.

[0089] Strips 1 and 2 showed slight negative images corresponding to the most powerful transducers. Background density was light gray. Strips 3 and 4 showed no images. They were uniformly dark. Strips 5 and 6 showed faint reversal images corresponding to the most powerful transducers. Strips 7 and 8 showed strong reversal images varying in size in proportion to the power range of the corresponding transducers.

Claims

1. An ultrasonographic process for preparing a visible image in an element comprised of a support having a silver halide emulsion layer, comprising exposing the element to ultrasound in an image pattern while the element is in contact with a liquid, and developing the element with a silver halide developer to produce a visible image defined by the ultrasonic exposure, characterized in that said silver halide emulsion contains internally fogged silver halide grains, said liquid is a transport liquid containing a diffusible solute capable of rendering the internally fogged silver halide grains developable in a surface developer.

2. A process according to claim 1 in which the step of contacting the element with the transport liquid and the step of developing the element are sequentially performed by bringing the element into contact with the developer following the ultrasonic exposure.

3. A process according to claim 1 in which the transport liquid is a surface silver halide developer, so that upon the ultrasonic exposure imagewise development of the element commences.

4. A process according to claim 1 in which the solute composes iodide ions.

5. A process according to claim 1 in which the solute comprises a silver halide solvent.

6. A process according to claim 1 in which the solute comprises a thiocyanate, a thioether, a thiosulfate or a sulfite compound.

7. A process according to claim 1 in which the exposure is pulsed ultrasonic radiation.

8. A process according to claim 1 in which the silver halide emulsion layer contains internally fogged converted-halide silver halide grains which are at least 50 mole percent bromide and less than 10 mole percent iodide, based on total halide.

9. A process according to claim 1 in which the step of developing the element is delayed, following -imagewise ultrasonic exposure, fcr a period sufficient to enhance further the development response of the element.

10. A process according to claim 1 in which the transport liquid contains iodide ions at a concentration of from 200 to 800 mg per liter of transport liquid.

11. A process according to claim 1 in which a silver halide developer is employed as the transport liquid.

12. A process according to claim 1 in which the silver halide emulsion comprises converted-halide silver halide grains are at least 90 mole percent bromide and less than 5 mole percent iodide, based on total halide, any remaining halide being chloride.

13. A process according to claim 1 in which the transport liquid contains thiocyanate ions at a concentration of from 5 to 15 grams per liter of transport liquid.

14. A process according to claim 1 in which the transport liquid contains thiosulfate ions at a concentration of from 0.5 to 5 grams per liter of transport liquid.

15. A process according to claim 1 in which the solute comprises a silver halide solvent, the element is exposed to ultrasound to dissolve silver halide selectively in exposed areas of the element and the element is developed to produce a positive silver image defined by the imagewise pattern of ultrasonic exposure.

Drawing